1. Field of the Invention
The present invention relates to a process for producing a resinous laminated member. Specifically, it relates to a process for producing a resinous laminated member, which comprises a first resinous layer, a second resinous layer and a decorated layer disposed to interpose between the first and second resinous layers, utilizing a film in-mold method. The present invention can be used suitably when producing electric-waves transmittable cover members. For example, an electric-waves transmittable cover member is disposed in an exterior component part, which is provided with a radar device in the rear and which has an opening formed therein. Specifically, the electric-waves transmittable cover member is disposed in the opening of the exterior component part so as to cover the opening. Thus, the electric-waves transmittable cover member can transmit electric waves, such as extremely-high-frequency waves and microwaves, which radar devices transmit and/or receive.
2. Description of the Related Art
As such an on-vehicle radar device, the following are available: laser type radar devices, which utilize laser beams; and electric-wave type radar devices, which utilize electric waves, such as extremely-high-frequency waves and microwaves. Among them, electric-waves type radar devices have been attracting engineers' attention, because they are less likely to be susceptible to environmental influences, such as rain, snow and fog, than laser type radar devices are. Moreover, electric-waves type radar devices can contribute to downsizing antennas, because short-wavelength electric waves, such as extremely-high-frequency waves, are good in terms of the rectilinearity and directivity.
Such on-vehicle radar devices transmit extremely-high-frequency waves, and receive extremely-high-frequency waves, which are reflected at physical objects after running into them. Thus, the on-vehicle radar devices are used for the purpose of detecting obstacles present in front of a vehicle, or measuring the distance between vehicles. Accordingly, on-vehicle radar devices have been disposed in the rear of a front grill, an exterior component part, which is disposed on the front surface of a vehicle. However, a front grill itself has been provided with a large number of ventilation openings for taking air in into the engine room of a vehicle. Moreover, the front grill's surface has been often subjected to metallic plating. Thus, the front grill is constructed so that electric waves, such as extremely-high-frequency waves which exhibit high reflection coefficients with respect to metal, are less likely to transmit through it satisfactorily. If a front grill is provided with an opening, which is positioned in front of an on-vehicle radar device, for permeating electric waves, it is possible to transmit electric waves through the opening. However, when such a front grill is left as it is without taking any precautions, it is possible to see the inside of an engine room, that is, the on-vehicle radar device disposed therein, through the opening. Consequently, such a front grill has impaired the decorativeness of a vehicle. Hence, a front garnish has been disposed in the opening for permeating electric waves, opening which is formed in a front grill, in order to enhance the decorativeness and electric-waves transmittability of the front grill. Note that such a front garnish is composed of an electric-waves transmittable material so that it works as an electric-waves transmittable cover member.
Japanese Unexamined Patent Publication (KOKAI) No. 2004-251,868 discloses such an electric-waves transmittable cover member, for instance. The electric-waves transmittable cover member comprises a transparent resinous layer, a substrate layer, and a decorated layer. The transparent resinous layer is composed of an electric-waves transmittable and transparent material. The substrate layer is disposed on the rear side of the transparent resinous layer, and is composed of an electric-waves transmittable material. The decorated layer is disposed between the transparent resinous layer and the substrate layer.
The conventional electric-waves transmittable cover member is produced utilizing a so-called film in-mold method. For example, a film is shaped to a predetermined configuration. The film comprises a film substrate, and a printed membrane, which has a predetermined decoration and is formed on the film substrate. While disposing the shaped film within a forming mold, the transparent resinous layer is formed on the printed-membrane side of the film, and then the film substrate is removed. Thus, a first molded body is formed, and is provided with a transfer membrane to which the printed membrane is transferred. Thereafter, the substrate layer is formed on the transfer-membrane side of the first molded body. Alternatively, a film is shaped to a predetermined configuration. The film comprises a film substrate, and a printed membrane, which has a predetermined decoration and is formed on the film substrate, similarly. While disposing the shaped film within a forming mold, the transparent resinous layer is formed on the printed-membrane side of the film. Thus, a first molded body is formed. Thereafter, the substrate layer is formed on the film-substrate side of the first molded body.
Moreover, in the conventional electric-waves transmittable cover member, the transparent resinous layer and the substrate layer have the inner surfaces, which face to each other, and the inner surfaces are provided with a predetermined irregularity, respectively, and the printed membrane with a predetermined decoration is disposed on the convexity of the irregularity, which is provided for the inner surface of the substrate layer, in order to enhance the decorativeness of the conventional electric-waves transmittable cover member, which is appreciated visually from the transparent-resinous-layer side.
In addition, in the conventional electric-waves transmittable cover member, the substrate layer is disposed on the rear side of the transparent resinous layer to make a laminated construction, and thereby the irregularity of the substrate layer absorbs the thickness fluctuation of the transparent resinous layer, which results from providing the irregularity for the transparent resinous layer, so as to make the thickness over the entire conventional electric-waves transmittable cover member constant. Thus, the conventional electric-waves transmittable cover member avoids such a drawback that the electric-waves transmittability has fluctuated between the thicker portions and the thinner portions.
Note that such a conventional electric-waves transmittable cover member is fastened to and held by a front grill in the following manner. For example, an engaging portion, such as an engagement projection, which protrudes from the rear surface of the substrate layer, is engaged with an engaged portion, such as an engagement hole, which is provided for the front grill, and thereby fixing the conventional electric-waves transmittable cover member onto the front grill.
Meanwhile, when a front grill inclines with respect the vertical direction so as to bulge from small to large as it extends downward, an electric-waves transmittable cover member, which is disposed in the opening of the front grill, can desirably have a transparent resinous layer whose outer surface inclines as well so as to agree with the inclining front grill, from the viewpoint of upgrading the decorativeness by enhancing the integrity between the front grill and the electric-waves transmittable cover member. In this instance, when the outer surface of the transparent resinous layer is formed as such an inclining surface, the rear surface of the substrate layer can desirably be formed as a similarly inclining surface so that the thickness over the entire conventional electric-waves transmittable cover member is made constant in order to inhibit the fluctuation of electric-waves transmittability, which results from the changing thickness. Likewise, in order that the conventional electric-waves transmittable cover member satisfactorily demonstrates such a decorative effect that the decoration of the printed membrane comes up three-dimensionally within the transparent resinous layer, the transparent resinous layer can desirably have a constant thickness. If such is the case, the inner surfaces of the transparent resinous layer and substrate layer, which face to each other, are formed as a similarly inclining surface, respectively.
However, when trying to produce an electric-waves transmittable cover member which comprises such inclining surfaces, there arise problems as hereinafter described.
That is, when utilizing a film in-mold method, a film is shaped to a predetermined configuration in advance, and then a transparent resinous layer, for instance, is molded while disposing the shaped film in a forming mold. Thus, it is possible to form the transparent resinous layer integrally with the film. However, from the viewpoint of improving the productivity, it is desirable to shape a film so as to conform to the inner-surface configuration of a transparent resinous layer simultaneously with the molding of the transparent resinous layer. Moreover, when forming a substrate layer integrally with the thus produced primary molded product, which comprises the transparent resinous layer and the film, to produce a secondary molded product, the secondary molded product is usually removed from the forming mold in the same direction as the primary molded product is removed therefrom. For example, when a primary molded product is molded using a primary forming mold, in which a movable mold moves in the horizontal direction to open and close the primary forming mold, and the resulting primary molded product is removed from the primary forming mold in the horizontal direction, a secondary molded product is molded using a secondary forming mold, in which a movable mold moves likewise in the horizontal direction to open and close the secondary forming mold, and the resulting secondary molded product is removed from the secondary forming mold in the horizontal direction. In this instance, since the engaging portion extends in the horizontal direction, it does not make an undercut. Thus, the secondary molded product can be removed from the secondary forming mold without using any sliding mold.
In such a mode that the secondary molded product is removed from the secondary forming mold, without utilizing any sliding mold, in the same direction as the primary molded product is removed from the primary forming mold, when trying to shape a film, which is extended in the vertical direction, simultaneously with the molding of a transparent resinous layer provided with an inclining inner surface, the film, which is extended in the vertical direction, is pressed onto a molding surface for molding the inclining inner surface. Accordingly, the displacement magnitude (or elongation magnitude) of the shaped film changes depending on the inclination of the molding surface, and has come to differ from parts to the other parts of the shaped film. For example, when the molding cavity surface for molding the inclining molding surface inclines with respect to the film, which is extended in the vertical direction, so as to separate away more from the film as it goes upward, the displacement magnitude of the film is larger at the upper parts of the shaped film. Consequently, the upper parts of the shaped film suffer from such problems that decorative deviations have occurred, that is, the decorative printed membrane, which is provided for the film, has deviated from a specifically-designed position; that the film substrate have been torn apart; and that the printed membrane has been cracked. Moreover, when the molding cavity surface for molding the inclining surface is provided with an irregularity, the film substrate and printed membrane cannot follow up the irregular configuration fully at the upper parts of the shaped film, which exhibit larger displacement magnitudes, so that the torn-off film substrate and the cracked printed membrane are likely to occur. Note that, from the viewpoint of inhibiting the decorative deviations, if a material, which is less likely to elongate, is employed to make the film substrate, the film substrate is more likely to be torn off.